Assessment of forage brassica species for dairy and beef-cattle fall grazing systems*

Abstract

Objectives: In temperate environments of the United States, winter forage management has traditionally necessitated either (a) feeding conserved forages or (b) stockpiling grazeable perennial forage. Forage brassicas might offer a low-cost alternative to these strategies. This project evaluated different annual forage brassicas in a temperate forage fall production system. Materials and Methods: Three brassicas, Barsica forage rape (Brassica napus L.), Inspiration canola (B. napus L.), and Appin turnip (B. rapa L.) were compared against KB Supreme annual ryegrass [(Lolium multiflorum Lam.) ARG] for DM yield and nutritive value over 2 fall seasons. Plot sizes were 5.5 × 9.1 m and seeded in August of 2015 and 2016 in a randomized complete block design with 4 replications. Harvests occurred at 2-wk intervals in 2015 and 2016. Results and Discussion: Brassica DM yields (734 to 861 kg of DM/ha) were greater (P < 0.001) than ARG (344 kg of DM/ha), and NEl (1.73 to 1.79 Mcal/kg), NEg (1.04 to 1.11 Mcal/kg), and NEm (1.65 to 1.72 Mcal/kg) concentrations in Inspiration canola and Barsica forage rape were greater than ARG (P < 0.001). Additionally, total nutrient yields (kg of DM/ha) of CP (176 to 204 kg of DM/ha) and NEl (1,200 to 1,500 Mcal/ha) were greater (P < 0.001) for brassicas than ARG (CP = 88 kg of DM/ha; NEl = 555 Mcal/ha). Implications and Applications: Brassicas had greater DM and nutrient yields, allowing for twice as many potential grazing days as ARG, thereby conceivably extending the grazing season with high-quality forage and reducing feeding costs.